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Clarification on development and differentiation from penis
The article currently states that it is the action of the protein TDF, from a gene on the Y chromosome, which determines whether the genital tubercule becomes a penis (should really be glans, or head, of the penis; the shaft comes from elsewhere) or a clitoris.
TDF determines whether the bipotential gonads become testes or ovaries. It's the testosterone and dihydrotestosterone from the testes that determines whether the tubercule becomes a glans penis or a clitoris.
Talarohk (talk) 07:23, 7 February 2019 (UTC)
See what the Genital tuberclecurrently states. The Clitoris article is simply following what the sources in the article relay. With regard to the genital tubercule, sources often word the matter as "either a clitoris or a penis." I understand what you are stating about the genital tubercule, but the literature has not always been consistent in that description. Like I've noted before, "some sources simply state that the genital tubercle forms the glans clitoris and glans penis, while other sources state the genital tubercle elongates and forms the shaft and glans of the penis, and that the genital tubercle forms the glans and shaft of the clitoris. In other words, sources do not only state that the genital tubercle only forms the glans of both organs. Nor do they usually state that genital tubercle only forms the glans of both organs." Below, see the sources I pointed to in that previous discussion. I haven't yet looked at newer sources for descriptions on the matter.
Click on this to see sources for differences in explaining the genital tubercle and urogenital folds matter.
For example, this 2003 Diagnostic Imaging of Fetal Anomalies source, from Lippincott Williams & Wilkins, page 606, states, "In males, the urogenital folds fuse and the genital tubercle elongates to form the shaft and glans of the penis."
This 2008 Peripheral Arterial Disease source, from McGraw Hill Professional, page 854, states, "The genital tubercle elongates to form the penis. The coronary sulcus on the genital tubercle demarcates the primordial glans penis from the phallic shaft."
This 2011 Lecture Notes: Biomedical Science source from John Wiley & Sons, page 245, states, "The genital tubercle elongates and forms the shaft and glans of the penis. The urogenital sinus becomes continuous with a groove that develops on the caudal face of the genital tubercle and this groove closes to become the penile part of the urethra while the fused urogenital folds enclosing the sinus becomes the prostate part of the urethra. [...] The genital tubercle forms the glans and shaft of the clitoris."
This 2013 Endocrinology: An Integrated Approach source, from CRC Press, page 224, states, "The genital tubercle elongates and forms the shaft and glans of the penis. [...] In the female, the labia minora form from the urethral folds and the genital tubercle elongates to form the clitoris."
This 2013 The 7 Sexes: Biology of Sex Determination source, from Indiana University Press, page 116, states, "DHT, in turn, acts on nuclear receptors in those cells and the genital tubercle forms the head of the penis, or the glans penis, as it is called in medical texts."
This 2014 Oxford Handbook of Endocrinology and Diabetes source, from Oxford University Press, page 544, states, "The genital tubercle elongates to form the corpora cavernosa and glans penis; the urethral fold forms the penile shaft, and the labioscrotal swelling forms the scrotum."
And this 2009 Reproductive Endocrinology & Infertility source, from BI Publications Pvt Ltd, shows where both [Jytdog] and [I] were coming from; it has the following layout:
Labioscrotal swellings -- Scrotum/Labia majora
Urogenital folds -- Ventral aspect of the penis/labia minora
Genital tubercle -- Penis/Clitoris
Urogenital sinus -- Urinary parts
Regarding the testis-determining factor (TDF), which is also known as the sex-determining region Y (SRY) protein, while the lead states that "the tubercle develops into either a penis or a clitoris, depending on the presence or absence of the protein tdf, which is codified by a single gene on the Y chromosome.", the lower part of the article (the Development section) states, "The Y chromosome contains a sex-determining gene (SRY) that encodes a transcription factor for the protein tdf (testis determining factor) and triggers the creation of testosterone and Anti-Müllerian hormone for the embryo's development into a male. [...] The clitoris develops from a phallic outgrowth in the embryo called the genital tubercle. Initially undifferentiated, the tubercle develops into either a clitoris or penis during development of the reproductive system depending on exposure to androgens (primarily male hormones)." ThisNature source used in the Development section states, "Once the SRY gene product stimulates the indifferent gonad to develop into a testis, the testis begins producing two hormones, testosterone and anti-Müllerian hormone, or AMH. Testosterone and one of its derivatives, dihydrotestosterone, induce formation of other organs in the male reproductive system, while AMH causes the degeneration of the Müllerian duct. In females, who do not contain the SRY protein, the ovary-forming pathway is activated by a different set of proteins. The fully developed ovary then produces estrogen, which triggers development of the uterus, oviducts, and cervix from the Müllerian duct."
The lead focused on TDF because of its role regarding the hormones. I'll go ahead and change the lead text from "depending on the presence or absence of the protein tdf, which is codified by a single gene on the Y chromosome" to "during development of the reproductive system depending on exposure to androgens (which are primarily male hormones)." If you want us to mention testosterone and dihydrotestosterone in the lead we can, but we can also mention dihydrotestosterone in the Development section. Flyer22 Reborn (talk) 01:11, 8 February 2019 (UTC)